PIK3CA and mismatch repair cancer syndrome 1: First, it has been suggested that mutations in KRAS, PIK3CA, and BRAF drive metabolic reprogramming toward the Warburg-effect (Levine and Puzio-Kuter 2010; Kimmelman 2015; Hutton et al. 2016; Jiang et al. 2018), and we have shown previously that MMR deficiency is associated with presence of the Warburg-effect (Offermans et al. 2021).